On visiting the cave, Mr. Wilson found an excavation in the floor made three or four years since by some persons digging for saltpetre-earth, partly filled in, but still several feet deep; and exposed at the sides of this pit were several rows of bodies placed in regular order one above another, in a remarkable state of preservation. They were in a compact position, the knees bent up to the chin, and the face drawn back close to the buttocks, then securely sewed up in the remarkably strong and well-woven cloth here presented, which, on all of the four or five bodies examined, showed the same degree of strength and perfection. Over this was another covering of palm-leaves also sewn closely together. The bodies were dried and shrunken, but retained their form and integuments. Under each body were two small sticks, on which the body was laid on its back, the feet towards the mouth of the cave. The circumference of the cave was about a hundred feet, and the height above the floor, thirty or forty feet. Mr. Wilson and his companions “came to the very decided conclusion,” that the floor of the cave, for a depth of twenty feet or more, was formed of bodies similarly arranged in layers which had been placed there from time to time, as they died, and covered with earth and pebbles from the sides of the mountains. There can be no doubt that a thorough exploration of these relics would reveal very much of the lost history of the Indian tribes of Mexico, and richly reward the labors of the antiquarian. The excellent material of the cloth in which the bodies were sewn up, surpassing in texture and strength anything now manufactured in Mexico, is worthy of investigation, as it may still be found valuable for making bags, sails, etc. There was no sign of any embalming substance by which the bodies and cloth could have been preserved, and the only explanation suggested by Mr. Wilson is that it is due to the dryness of the atmosphere, and the saltpetre contained in the earth. He also suggested that the fibres of the cloth may have been derived from the “Maguey,” (Agave Americana) or some allied plant. Dr. Cooper remarked that the condition of the foot was very similar to those of the Indian Mummy presented to the Academy by Dr. J. B. Stout, January 21st, 1856, and which had been dried by the action of the air, while protected from the weather by a cedar canoe inverted over another containing the body. That was in the moist climate of Shoalwater Bay, north of the Columbia river, and Dr. Cooper who was present at the time the body was removed by Capt. Russell in 1854, was a witness of the fact that no preservatives had been found with it. He also stated that the Indians of the vicinity could not tell how long it had been there, though certainly not a hundred years. REGULAR MEETING, AUGUST 1ST, 1864.